For over 250 years the secret to building violins with the power and tonal quality of those made by the pupils and descendants of Andrea Amati has been lost. Amati of Cremona, Italy, and in particular, his students Antonio Stradivari and Giuseppe Guarneri, produced instruments of such extraordinarily high quality that even today it is impossible to duplicate their work. Stradivari and Guarneri died with their violin making secrets, and great effort has been expended in attempting to find the secrets behind the exceptional tone and power of the Cremonese violins.
In order to discover the secrets behind the tone and power of great violins, it is first necessary to understand how violins are made, and how they produce sound. A violin is basically a set of strings mounted on a wooden box. Energy from vibrations that are induced by drawing a bow across the strings is transferred to the box and air space enclosed by the box. The vibrations of the wood in the violin set the air in the box in motion to produce sound waves. The tone and power of the instrument depend on the transfer of the vibrational energy of the strings to the box and to the surrounding air.
A more detailed understanding of violin acoustics is presented in "The Physics of Violins," The Scientific American, 207 (November 1982) pages 76-94, herein incorporated by reference. As noted above, when playing violin type instruments, vigorously drawing a bow across the strings causes them to vibrate. Since unamplified strings have insufficient surface area to set an appreciable amount of air in motion, the string vibrational energy is communicated through the wooden body of the violin through the complex motions of the violin bridge. Each of the strings vibrates at a particular frequency, and forces the box to vibrate at that particular rate. The amplitude of vibration in the box depends upon the strength or amplitude of the string vibration. However, different string tones are not amplified equally. The wooden structure itself has multiple natural vibration frequencies, some of which coincide with string harmonic frequencies. The coincidence of a string harmonic frequency with a resident frequency in the wood results in enhanced transfer of energy from the string to the box causing greater amplification of that particular tone.
Controlling the tone and amplitude in violin-type instruments is a challenging and difficult task. Numerous factors influence the tone and power of these instruments. For example, the choice of wood, the shape and thickness of the wood, and the varnish applied to the wood have all been characterized as critical factors in producing high quality violin-type instruments. The relative importance of material, dimensions and construction, and varnish are classified in Antonio Stradivari, His Life and Work (1644-1737) by W. Henry Hill, Arthur F. Hill, F.S.A., and Alfred E. Hill, published by Dover Publications, Inc., New York (1963), and herein incorporated by reference. Hill et. al. classified varnish as the most important element in producing a good violin, with construction and dimensions being the second most important element, and material being the third most important element.
Researchers have concentrated on duplicating the exact structure of the violins produced by Stradivari and the other great violin makers of Cremona. Some of these experiments were discussed in the Oct. 11, 1981 televised broadcast of Nova on PBS entitled The Great Violin Mystery Nova #813, available from WGBH Transcripts, Boston, Mass., and herein incorporated by reference. One researcher, Jack Fry, discovered that the thickness of the wooden backs of violins produced by the great Cremonese violin maker, Guarneri Del Gesu, were slightly asymmetrical, and later measurements of other great Italian instruments revealed similar asymmetry. The asymmetry appears to be intentional to adjust for the asymmetrical positioning of the sound post in the violins. Better quality violins are now made by duplicating this asymmetry, but these violins still lack the tonal quality achieved by the Cremonese violin makers.
Fry also attempted to experiment with different varnishes and methods of application. One experiment involved application of a solution of resins to the inside of a violin, and heating it to try to force the varnish into the wood. However, the effect this had on the stiffness of the wood and the resulting sound of the violin was not discussed.
Fry, among others, recognized that varnishes play a critical role in changing the ultimate stiffness and tone of violins, but the prior art could not control the impregnation of wood with varnishes to the same degree that the thickness of the wood could be graduated. Hence, while researchers have been able to duplicate many of the physical characteristics of the Cremonese violins, they have been unsuccessful in producing violins having the power and tone of a Stradivarius or a Guanerius. The missing ingredient appears to be the particular varnish used and method of application.
The prior art has recognized the importance of the types of material used and the exquisite detail necessary for construction of violins of the same quality as those produced by Stradivari and the other great violin makers of Cremona. The importance of varnish in modifying the tone of the violins has also been recognized, but there remains a need for an effective method of applying the varnish to the violin wood such that violin type instruments can be produced having improved tone and power.